Ion-conducting membrane for fuel cell

Abstract

Ion-conducting membranes for fuel cells are disclosed. The membrane is composed of a hydrogenated and sulfonated statistical copolymer of styrene and butadiene. A preferred membrane is obtained by hydrogenating a copolymer of styrene and butadiene to obtain less than five percent residual unsaturation, then sulfonating the polymer with an acetyl sulfate sulfonation agent to a level of at least 30 mol % percent sulfonate.

We claim: 
     
       1. A water-insoluble proton-conducting statistical copolymer comprising structural units of formula (I), (II), (III) and (IV) ##STR2## wherein m, n, p and q are integers from 250-10,000 and q is from 20% to 80% of the quantity (p+q). 
     
     
       2. The copolymer of claim 1 wherein the quantity (p+q) is from 15% to 99% of the quantity (m+n+p+q). 
     
     
       3. The copolymer of claim 2 wherein q is from 20% to 50% of the quantity (p+q). 
     
     
       4. The copolymer of claim 2 wherein q is 30% of the quantity (p+q). 
     
     
       5. A fuel cell comprised of: (a) a proton-conducting membrane composed of the copolymer of claim 1;   (b) first and second opposed electrodes in contact with said proton conducting membrane;   (c) means for supplying a fuel to said first electrode; and   (d) means for permitting an oxidant to contact said second electrode.